Improvement in circle-dividing instruments



Patent iis June 19,-18-77.

N.PETERS PHOTO-LATHOGRAPHER, WASHINGTON, D .C,

2 Sheets-Sheet 2..

M. manna CIRCLE-DIVIDING INSTRUMENT.

Patented June 19, 1877.

No.19Z,093.

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' adapted for ascertaining the radius of the re- -in full lines and theother in dotted lines,

UNITED STATES.

PATENT OFFICE;

MYRON STOLP, or AURORA, ILLINOIS.

IMPROVEMENT IN CIRCLE- DIVIDING INSTRUMENTS.

TSpecification'forming part of Letters Patent No. 192,093, dated June19, 1877 application filed January To all whom it may concern: T

Be it known that I, MYRON G. SToLP, of Aurora, in the county of Kane andState of Illinois, have invented certain new and useful Improvements inCircle-Dividing Instruments; and I do hereby declare that the followingis a full, clear, and exact description thereof, which will enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and to theletters of reference marked thereon, which form part of thisspecification.

My invention consists'in a novel construction of instrument for dividinga circle into any required number of'parts, however minute, and whichis, at the same time, adapted for the dividing arrangement of agear-cutter or dividing engine, and which is also quired pitch-circlefor blanks for gear-wheels when the number of teeth and the pitch of theteeth are given, and which is also adapted for use as a protractor forlaying out an angle, and for similar and kindred purposes.

In the drawings, Figure 1 is a perspective viewof my improvedinstrument. Fig. 2 is a topview with the spacing-pin in the hollow studo, and with the pin and theedge 5 6 of the T square in contact, and withthe latter and the diametric marking-arm I, shown also in dotted linesin another position 5 Fig. 3, a top View, with the diametric markingarmshown at two different angles, one being Figs. 4 and 5, diagramsrepresenting different modes of ascertaining the pitch of wheels;-andFigs. 6,7, and 8, parts detached.

A is abed or bar, having on its upper side a dovetailed groove, 1),adapted to receive the head of the T square 0, and permit it to beheldand slid in a straight line therein. A bracket or projection, 01, onsaid bar A supports thejournal or'journal-pin e of a wheel, F, aroundwhose .periphery wind flexible metallic or other bands g g 9, thesehands .being secured, if desired, at one end to the pe riphery of thewheel, and at their other end or endsto the respective ends h IL of thehead of the T square, these bands winding in opposite directions uponthe wheel, so that when the wheel is turned upon its axis it shallcoincidently shift the T square to the right or left a distancecorresponding tothat moved by a given point in the periphery of thewheel F, the full extent of traverse of the T square being, forconvenience, equal to one-half the circumference of the wheel F, or alittle in excess thereof. j

Iis a marking bar or rule affixed to the wheelF, and having astraight-edge,jj, in a line dialnetric with this wheel, such barprojecting beyond the wheel at its two opposite sides, one arm beinglonger than the other, and this bar also serves as a handle or lever bywhich to turn the wheel as may be required, and it standsoff far enoughfrom the wheel to permit its being turned without any obstruction, and,when so turned, the shorter arm may pass freely beneath the bed A as thelatter is lying upon the table, projections or feet k k at the ends ofbed A elevating it sufficiently for this purpose. Staple-pins l l,passing through appropriate holes in these feet, serve to secure the bedA to a tablewhen the" instrument is to be used. Adjusting: screws m mserve to tighten or loosen the bands 9 g g, as may be desired. A bracketor projection, n, on the bed A is provided with a hollow stud or nipple,0, on which may be hung and swung the graduated division-scale P. Whenthe scale is hung on the stud 0 the hole 20 answers for the zero-pointof the scale, the graduations, for convenience sake, beingin equalmeasurements from zero to 90, and a hole being made in this bar forevery one of these divisions; and the bar is further provided at itsextremity or free end with a projectiom-Q, drilled with holes to receivea staple, r, or pins, by which it maybe secured to the table at anyrequired angle toedge 5 6 ofthe T square. It has also a verticalprojection or angle-pin, s, which is in the ninetieth hole, and servingas a stop when it comes in contact with the edge 5 6 of the T square inlaying out angles. The blade of the T square, and its edge 5 6, in itsmovements may pass over all parts of the length of the divisionscale,the extremity of the T square resting upon a foot, t, which elevates itsufficiently for the purpose.

A center-pin, u, passing through the axis of point, by which it may bepressed into the ta-' ble and hold its position while the instrument isbeing used. A spacing-pin, 22, adapted for the hole in the stud 0, andalso for any of the holes of the graduated scale, serves for purposespresently to be described.

The following will illustrate some of the uses to which this instrumentis applied and the manner of using it: Suppose it be required to dividea circle accurately into any required number of parts. As shown in Fig.2, draw the line 1 2, and upon this, as a diameter, describe the circle12 3 4, having a radius less than the length of the shorter arm of themarking-rule I; place the instrument over the center of this circle bymeans of the centering-pin u, and secure it there by pressing the pininto the table; slide the T square until its edge 5 6 is to the left ofthe zero-hole w in the stud place the spacing-pin o in the zero-hole inthe stud 0, and slide the T square until its edge 6 touches this pin 1;,still, as yet, keeping the pin and edge in contact; bring the instrumentso that the straight-edge of the rule I shall coincide with the diameter1 2; press in the staple or thumb-tack l, and also that at l, when thehead of the T square will permit it; remove the pin '0 and take hold ofthe longer arm of the rule I at its end, and move it half-way around orthrough a semi-circumference until the rule takes the position shown inthe dotted lines in Fig. 2. The T square will then be in the positionshown also in dotted lines in Fig. 2. Next place the scale ordivision-bar P on the stud 0,'its zero-hole being thus the center of thestud, and with the angle-pin 8 off to the right of the edge 5 6, asshown in Fig. 2. The instrument is now in position for dividing thecircle or for laying out an angle. It will be seen that only one-halfthe circumference of the wheel is used, (this is for convenience onlythewhole or part of the circumference might be used, if desired;) and thatthe distance through which the edge 5 6 has moved to take the newposition (shown in dotted lines in Fig. 2) is exactly one-half thecircumference of the wheel F. Now, to divide the circle into, say,twenty equal parts, place the spacing-pin v in the hole 60 of scale P,and swing the pin against the edge 5 6 in the position of the dottedlines in Fig. 2; press in the thumb-tack at 1; move the edge 5 6 so asto allow the pin '0 to be shifted to the left and placed in hole 54;slide the edge 5 6 back until it is in contact with pin 22, now in hole54. In this I position the longer'arm of the marking-arm I will be foundto have moved through one-twentieth ,)of the circumference, and ofcourse the shorter arm will have moved through the same distance, and,therefore, a line drawn along the straight-edge of the arm I on bothsides of the center of the wheel, cutting the circle at 20 20, will marktwo divisions of onetwentieth of the circle each, or eighteen degrees.Repeating this operation and shifting the pin 4; six holes farthertoward the zerohole of the scale-that is, to hole 48-will give two moredivisions of one-twentieth of the circle to be marked off, and so onsuccessively until the whole circle shall have been divided into therequired twenty parts. If the spacingpin 0 had been placed one hole tothe left instead of six the circle would have been divided into onehundred and twenty (120) equal parts, or six times too many. Iftwenty-three divisions be desired, place the pin '1; in hole 46 (or in69) and move the pin four (or six) holes, or twice the multiplier ofrequired number of divisions, and generally by moving the pin onehole-at a time the circle is divided into twice the number of partsindicated by the hole used in setting the division-scale at the correctangle.

To ascertain the pitch-circle fora gear or blank of a certain number ofteeth and predetermined pitch, I proceed as follows: Suppose the gear tohave twenty-one teeth and exactly one inch pitch. First set theinstrument as above described, and lay off one division on any circle,as shown by the dotted are in Fig. 4, take the pitch of one inch betweenthe points of common dividers, and move the points of the dividers alongthe'lines 1 3 and 9 3(which include the division so laidoff) until thepoints rest on both lines, as shown, the center of the dividers 10 beingmoved on the bisecting line 2 5: the point 4 is the required point, and4 3 or 3 6 are the radii of the required pitch-circle.

The same result above obtained can also be arrived at by construction,referring to Fig. 5. Draw the line 13 14, bisecting the angles l5 l6 l7and 18 16 19; erect the perpendiculars 20 21 and 14 23, making them eachequal to one-half( l) the required pitch, or one-halfinch; draw the line21 23, and the point 24, where this line cuts the line 17 16, is therequired point, and 24 16 is the radius of the required circle. In thesame manner the radius of the outside circle for blanks or gears may beobtained.

To lay out an angle, after setting the in strument as described foreither of the preceding problems, instead of moving or turning themarking-arm I one-half way around, turn it only one-fourth (51-) around,as shown in Fig. 3, and swing the division-scale P until the angle-pinsis in contact with the edge 5 6 of the T square; then press in thethumbtack at r. The angle-pin s is in the ninetieth hole of the scale,and when the division-bar is at this angle and the edge 5 6 of the Tsquare is brought in contact with the pin 8, the longer arm ofmarking-bar I shows ninety degrees. If forty-five degrees are wanted,place the spacing-pin o in the hole numbered slide the edge 5 6 until incontact with this pin 12; then mark the angle across the circumferenceof the circle. Proceed as above for other angles.

In the same manner that ninety degrees is divided into ninety parts itis evident that any other part of a circle, however minute, can bedivided into ninety parts. Therefore, if forty-five degrees be dividedinto ninety parts, the divisions are one-half degrees,-or of the circle;dividing this one-half degree or 75 into ninety parts, the divisionswould be x of a circle.

There is, in fact, practically no limit to the number of divisions.

The instrument is simple, durable, has but few parts, cannot easily getout of order, and is most efficient in use for a wide range of duties,and-for accurate work, and with but little practice can be worked withgreat facility and rapidity. I

I can use the whole or any part of the circumference, as preferred. Individing the circle the T square moves a distance exactly equal to thesemi-circumference of the circle, whose-radius is that of the wheel; or,in other words, the circumference or any part of it is reduced to astraight'line', and then this whole or part is divided into any desirednumber of parts by means of changing the angle of the dividing scale,rule, screw, or other equivalentdevice on which are equal divisions.

I claiin- 1. A circle-dividing instrument in which a rule adapted toturn upon a center actuates a shifting square, substantially as and forthe purpose set forth.

, 2. In combination with the bed or support, the wheel E and the bar I,affix'ed thereto and adapted to' revolve therewith, and having astraight marking-edge coinciding with the diameter of the wheel,substantially as and for the purpose described.

its zero-point adapted for connection with the.

bed, and at its other extremity adapted to be secured to a table, andprovided with a projection or pin, .9, substantially as shown anddescribed.

7. In combination with the wheel, T square, and straps, adjustingdevices for adjusting the tension of the straps, substantially as shownand described. 1

8. In combination with the bed, the wheel F, and bar I, thecentering-pin u, whereby the wheel may be centered and retained inposition.

9. In combination, the bed, T square, and their connecting devices, barI, and graduated bar P, substantially as and for the purpose set forth.

In testimony that I claim the foregoing as my own I aflix my signaturesin presence of two witnesses. I

MYROK G. STOLP.

Witnesses:

JOHN MCARTHUR, LEVI D. MEAD.

